Package structure and method for forming the same

ABSTRACT

A package structure and method for forming the same are provided. The package structure includes a first through via structure formed in a substrate and a semiconductor die formed below the first through via structure. The package structure further includes a conductive structure formed in a passivation layer over the substrate. The conductive structure includes a first via portion and a second via portion, the first via portion is directly over the first through via structure, and there is no conductive material directly below and in direct contact with the second via portion.

BACKGROUND

Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductive layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon. Many integrated circuits are typically manufactured on a single semiconductor wafer, and individual dies on the wafer are singulated by sawing between the integrated circuits along a scribe line. The individual dies are typically packaged separately, in multi-chip modules, for example, or in other types of packaging.

New packaging technologies, such as package on package (PoP), have begun to be developed, in which a top package with a device die is bonded to a bottom package, with another device die. By adopting the new packaging technologies, various packages with different or similar functions can be integrated together.

Although existing package structures and methods of fabricating a package structure have generally been adequate for their intended purposes, they have not been entirely satisfactory in all respects.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It should be noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIGS. 1A-1I show cross-sectional representations of various stages of forming a package structure, in accordance with some embodiments of the disclosure.

FIG. 1I′ shows a cross-sectional representation of a package structure, in accordance with some embodiments of the disclosure.

FIG. 2A shows a top-view representation of the first opening and the second opening taken along line A-A′ of FIG. 1F, in accordance with some embodiments of the disclosure.

FIG. 2B shows a top-view representation of the first via portion and the second via portion taken along line B-B′ of FIG. 1Q in accordance with some embodiments of the disclosure.

FIG. 2C shows a top-view representation of the first via portion and the second via portion, in accordance with some embodiments of the disclosure.

FIG. 2D shows a top-view representation of the first via portion and the second via portion along line D-D′ of FIG. 1Q in accordance with some embodiments of the disclosure.

FIG. 3 shows an enlarged representation of the region A in FIG. 1I in accordance with some embodiments of the disclosure.

FIG. 4A-4B show cross-sectional representations of various stages of forming the first portion and the second portion of the conductive structure of a package structure, in accordance with some embodiments of the disclosure.

FIG. 4C shows a top-view representation of the first via portion and the second via portion taken along line C-C′ of FIG. 4B, in accordance with some embodiments of the disclosure.

FIG. 5A shows a top-view representation of the conductive structure, in accordance with some embodiments of the disclosure.

FIG. 5B shows a top-view representation of positional relationship between the conductive structure and the conductive connector, in accordance with some embodiments of the disclosure.

FIGS. 6A-6E show cross-sectional representations of various stages of forming the package structure, in accordance with some embodiments of the disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the subject matter provided. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Some variations of the embodiments are described. Throughout the various views and illustrative embodiments, like reference numbers are used to designate like elements. It should be understood that additional operations can be provided before, during, and after the method, and some of the operations described can be replaced or eliminated for other embodiments of the method.

Other features and processes may also be included. For example, testing structures may be included to aid in the verification testing of the 3D packaging or 3DIC devices. The testing structures may include, for example, test pads formed in a redistribution layer or on a substrate that allows the testing of the 3D packaging or 3DIC, the use of probes and/or probe cards, and the like. The verification testing may be performed on intermediate structures as well as the final structure. Additionally, the structures and methods disclosed herein may be used in conjunction with testing methodologies that incorporate intermediate verification of known good dies to increase the yield and decrease costs.

Embodiments for a package structure and method for forming the same are provided. FIGS. 1A-1I show cross-sectional representations of various stages of forming a package structure 100 a, in accordance with some embodiments of the disclosure. The package structure 100 a may be a chip-on-wafer-on-substrate (CoWoS) package or another suitable package. The package structure 100 a includes a through via structure over a semiconductor die, and a conductive structure formed over the through via structure. The conductive structure includes a first via portion and a second via portion. The first via portion has two ends for connecting, but the second via portion has one end for connecting. The formation of the second via portion is used to reduce stress and to prevent the formation of cracks and voids.

As shown in FIG. 1A, a substrate 102 is provided. The substrate 102 includes a front surface 102 a and a back surface 102 b. The substrate 102 may be made of silicon or other semiconductor materials. Alternatively or additionally, the substrate 102 may include other elementary semiconductor materials such as germanium. In some embodiments, the substrate 102 is made of a compound semiconductor such as silicon carbide, gallium arsenic, indium arsenide, or indium phosphide. In some embodiments, the substrate 102 is made of an alloy semiconductor such as silicon germanium, silicon germanium carbide, gallium arsenic phosphide, or gallium indium phosphide. In some embodiments, the substrate 102 includes an epitaxial layer. For example, the substrate 102 has an epitaxial layer overlying a bulk semiconductor.

A number of conductive structures 104 are formed in the substrate 102. The conductive structures 104 extend from the front surface 102 a of the substrate 102 towards the back surface 102 b of the substrate 102. In some embodiments, the conductive structures 104 are formed by forming a number of trenches (not shown) which extend from the front surface 102 a of the substrate 102. Afterwards, a barrier layer 103 is filled into each of the trenches, and the conductive structure 104 is formed on the barrier layer 103 and in each of the trenches.

An interconnect structure 110 is formed over the conductive structures 104 and the substrate 102. The interconnect structure 110 may be used as a redistribution (RDL) structure for routing. The interconnect structure 110 includes multiple conductive layers 114 and conductive pads 116 formed in multiple dielectric layers 112. In some embodiments, the conductive pads 116 are exposed at or protruding from the top surface of the top of the dielectric layers 112 to serve as bonding pads.

The dielectric layers 112 may be made of or include one or more polymer materials. The polymer material(s) may include polybenzoxazole (PBO), polyimide (PI), one or more other suitable polymer materials, or a combination thereof. In some embodiments, some or all of the dielectric layers 112 are made of or include dielectric materials other than polymer materials. The dielectric material may include silicon oxide, silicon carbide, silicon nitride, silicon oxynitride, one or more other suitable materials, or a combination thereof.

The conductive layers 114 and the conductive pads 116 may be made of copper (Cu), copper alloy, aluminum (Al), aluminum alloy, tungsten (W), tungsten alloy, titanium (Ti), titanium alloy, tantalum (Ta) or tantalum alloy. In some embodiments, the conductive layers 114 and the conductive pads 116 are formed by an electroplating, electroless plating, printing, a chemical vapor deposition (CVD) process, or a physical vapor deposition (PVD) process.

Afterwards, as shown in FIG. 1B, a semiconductor die 120 is formed over the conductive layer 116, in accordance with some embodiments of the disclosure. The semiconductor die 120 includes a substrate 121 and an interconnect structure 122 over the substrate 121. The interconnect structure 122 of the semiconductor die 120 includes a number of conductive layers 124.

In some embodiments, the semiconductor die 120 is sawed from a wafer, and may be a “known-good-die”. The semiconductor die 120 may be a system-on-chip (SoC) chip or memory die. In some other embodiments, the semiconductor die 120 is a system on integrated circuit (SoIC) device that includes two or more chips with integrated functions. In some embodiments, the memory die includes a static random access memory (SRAM) device, a dynamic random access memory (DRAM) device, a high bandwidth memory (HBM) or another memory dies. The number of semiconductor dies 120 is not limited to two, and the number can be adjusted according to actual application.

In some embodiments, a number of conductive pads 126 are formed below the conductive layers 124 of the semiconductor die 120, and each of the conductive pads 126 is bonded to each of the conductive pads 116 through a number of conductive connectors 128.

The conductive pads 126 are made of metal materials, such as copper (Cu), copper alloy, aluminum (Al), aluminum alloy, tungsten (W), tungsten alloy, titanium (Ti), titanium alloy, tantalum (Ta) or tantalum alloy. In some embodiments, the conductive pad 126 is formed by an electroplating, electroless plating, printing, a chemical vapor deposition (CVD) process, or a physical vapor deposition (PVD) process.

The conductive connector 128 is made of solder materials, such as tin (Sn), tin-silver (SnAg), tin-lead (SnPb), tin-copper (SnCu), tin-silver-copper (SnAgCu), tin-silver-zinc (SnAgZn), tin-zinc (SnZn), tin-bismuth-indium (SnBiIn), tin-indium (SnIn), tin-gold (SnAu), tin-zinc-indium (SnZnIn), tin-silver-Antimony (SnAgSb) or another applicable material. In some embodiments, the conductive connector 128 is formed by electroplating, electroless plating, printing, a chemical vapor deposition (CVD) process, or a physical vapor deposition (PVD) process.

Next, as shown in FIG. 1C, an underfill layer 130 is formed between the semiconductor die 120 and the interconnect structure 110, in accordance with some embodiments of the disclosure. The underfill layer 130 surrounds and protects the conductive connectors 128. In some embodiments, the underfill layer 130 is in direct contact with the conductive connectors 128.

In some embodiments, the underfill layer 130 is made of or includes a polymer material. The underfill layer 130 may include an epoxy-based resin. In some embodiments, the underfill layer 130 includes fillers dispersed in the epoxy-based resin.

In some embodiments, the formation of the underfill layer 130 involves an injecting process, a spin-on process, a dispensing process, a film lamination process, an application process, one or more other applicable processes, or a combination thereof. In some embodiments, a thermal curing process is used during the formation of the underfill layer 130.

Afterwards, a package layer 136 is formed over the underfill layer 130. There is an interface between the underfill layer 130 and the package layer 136, and the interface is lower than the top surface of the semiconductor die 120. The package layer 136 surrounds and protects the semiconductor dies 120. In some embodiments, the package layer 136 is in direct contact with portions of the semiconductor dies 120.

The package layer 136 is made of a molding compound material. The molding compound material may include a polymer material, such as an epoxy-based resin with fillers dispersed therein. In some embodiments, a liquid molding compound material is applied over the semiconductor dies 120. The liquid molding compound material may flow into a space between the semiconductor dies 120. A thermal process is then used to cure the liquid molding compound material and to transform it into the package layer 136.

Afterwards, as shown in FIG. 1D, a portion of the package layer 136 is removed, in accordance with some embodiments of the disclosure. As a result, the top surface of the semiconductor dies 120 is exposed. The top surface of the semiconductor die 120 is substantially level with the top surface of the package layer 136. Where applicable, the term “substantially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, including 100%.

In some embodiments, the package layer 136 is thinned using a planarization process. The planarization process may include a chemical mechanical polishing (CMP) process, a grinding process, an etching process, another applicable process, or a combination thereof.

Next, as shown in FIG. 1E, the substrate 102 is turned upside down and placed over a carrier substrate 139, in accordance with some embodiments. In some embodiments, the carrier substrate 139 is used as a temporary substrate. The temporary substrate provides mechanical and structural support during subsequent processing steps, such as those described in more detail later. The carrier substrate 139 is made of a semiconductor material, ceramic material, polymer material, metal material, another suitable material, or a combination thereof. In some embodiments, the carrier substrate 139 is a glass substrate. In some other embodiments, the carrier substrate 139 is a semiconductor substrate, such as a silicon wafer.

Afterwards, the substrate 102 is thinned using the carrier substrate 139 as support. In some embodiments, the substrate 102 is thinned from the back surface 102 b until the conductive structures 104 are exposed. In some embodiments, the conductive structures 104 and the barrier layer 103 become exposed and penetrate through the thinned substrate 102. As a result, a through via structure 108 is formed in the substrate 102. In some embodiments, the through via structure 108 is a through substrate via (TSV) structure. In some other embodiments, the through via structure 108 may be referred to as through-silicon via.

Afterwards, as shown in FIG. 1F, the carrier substrate 139 is removed, and a first passivation layer 140 is formed over the back surface 102 b of the substrate 102, in accordance with some embodiments of the disclosure. A first opening 141 is formed in the first passivation layer 140 to expose the through via structure 108, and a second opening 145 is formed in the first passivation layer 140 to expose the substrate 102. The first opening 141 has sloped sidewall surfaces, and the second opening 145 also has sloped sidewall surfaces.

The first passivation layer 140 is made of poly(p-phenylene-2,6-benzoxazole) (PBO), benzocyclobutene (BCB), silicone, acrylates, siloxane, another suitable material, or a combination thereof. In some other embodiments, the first passivation layer 140 is made of non-organic materials. The non-organic materials include silicon oxide, un-doped silicate glass, silicon oxynitride, silicon nitride, silicon carbide, another suitable material, or a combination thereof. In some embodiments, the first passivation layer 140 is formed by a deposition process, such as a physical vapor deposition (PVD) process, a chemical vapor deposition (CVD) process, or another applicable process.

The first opening 141 and the second opening 145 are formed by a patterning process. The patterning process includes a photolithography process and an etching process. The photolithography process includes photoresist coating (e.g., spin-on coating), soft baking, mask aligning, exposure, post-exposure baking, developing the photoresist, rinsing and drying (e.g., hard baking). The etching process may include a dry etching process or a wet etching process.

FIG. 2A shows a top-view representation of the first opening 141 and the second opening 145 taken along line A-A′ of FIG. 1F, in accordance with some embodiments of the disclosure.

The first opening 141 has a circular shape when seen from a top-view, and the second opening 145 has a circular shape when seen from a top-view. A diameter of the first opening 141 tapers gradually from top to bottom, and a diameter of the second opening 145 tapers gradually from top to bottom. In some embodiments, a bottom surface of the first opening 141 has a first diameter D₁, and a bottom surface of the second opening 145 has a second diameter D₂. The second diameter D₂ is greater than the first diameter D₁. In some embodiments, the first diameter D₁ of the bottom surface of the first opening 141 is in a range from about 15 μm to about 20 μm. In some embodiments, the second diameter D₂ of the bottom surface of the second opening 145 is in a range from about 40 μm to about 50 μm.

Next, as shown in FIG. 1G a conductive material is formed in the first opening 141 and the second opening 145 to form a conductive structure 148, in accordance with some embodiments of the disclosure. As a result, the conductive structure 148 includes a first portion 148 ₁ and a second portion 148 ₂. The first portion 148 ₁ includes a first via portion 148 a in the first opening 141, and a first metal portion 148 b on the first via portion 148 a. The second portion 148 ₂ includes a second via portion 148 c in the second opening 145, and a second metal portion 148 d on the second via portion 148 c. The bottom surface of the first via portion 148 a is level with the bottom surface of second via portion 148 c. The dot line shown in FIG. 1G is drawn to provide a better understanding of the structure, but there is no actual interface or boundary between the first via portion 148 a and the first metal portion 148 b, and between the second via portion 148 c and the second metal portion 148 d.

It should be noted that the first via portion 148 a has a first end and a second end in a vertical direction, the first end is in direct contact with the through via structure 108, and the second end is in direct contact with the first metal portion 148 b. The second via portion 148 c has a first end and a second end in a vertical direction, the first end is in direct contact with the substrate 102, and the second end is in direct contact with the second metal portion 148 d. The first metal portion 148 b is physically and electrically connected to the second metal portion 148 d. The second via portion 148 c is electrically connected to the through via structure 108 by the second metal portion 148 d, the first metal portion 148 b and the first via portion 148 a.

It should be noted that the first via portion 148 a has two ends to electrically connect to other conductive material, but the second via portion 148 c has one end to electrically connect to other conductive material. The entirety of the bottom surface of the second via portion 148 c is in direct contact with the substrate 102. Therefore, no conductive layer or material is directly below and in direct contact with the second via portion 148 c. The bottom surface of the second via portion 148 c is not direct contact with a conductive material or layer. The first metal portion 148 b has a recessed top surface, and the second metal portion 148 d also has a recessed top surface. The second via portion 148 c is between two adjacent through via structures 108.

After the conductive material is formed in the first opening 141, the second opening 145 and over the substrate 102, a portion of the conductive material is removed to form the conductive structure 148 by an etching process, such as a dry etching process, or a wet etching process.

The conductive material may be made of copper (Cu), copper alloy, aluminum (Al), aluminum alloy, tungsten (W), tungsten alloy, titanium (Ti), titanium alloy, tantalum (Ta) or tantalum alloy. In some embodiments, the conductive material is formed by an electroplating, electroless plating, printing, a chemical vapor deposition (CVD) process, or a physical vapor deposition (PVD) process.

FIG. 2B shows a top-view representation of the first via portion 148 a and the second via portion 148 c taken along line B-B′ of FIG. 1G in accordance with some embodiments of the disclosure.

As shown in FIG. 2B, the second via portion 148 c is separated from the first via portion 148 a by the first passivation layer 140 along line B-B′ in a horizontal direction. The width or the diameter of the second via portion 148 c is greater than the width or the diameter of the first via portion 148 a.

FIG. 2C shows a top-view representation of the first via portion 148 a and the second via portion 148 c, in accordance with some embodiments of the disclosure. FIG. 1G shows a cross-sectional representation taken along line C-C′ of FIG. 2C, in accordance with some embodiments of the disclosure. FIG. 2B is a portion of FIG. 2C, and FIG. 2C shows the positional relationship between the second via portion 148 c and the semiconductor die 120.

As shown in FIG. 2C, in some embodiments, the second via portion 148 c is located at peripheral region which is outside of the semiconductor die 120. The second via portion 148 c is located at the corner of the semiconductor die 120. In some embodiments, the second via portion 148 c is located at a middle portion between two adjacent semiconductor dies 120. In some other embodiments, the second via portion 148 c is located directly on the semiconductor die 120.

FIG. 2D shows a top-view representation of the first via portion 148 a and the second via portion 148 c along line D-D′ of FIG. 1I in accordance with some embodiments of the disclosure.

As shown in FIG. 2D, the first metal portion 148 b and the second metal portion 148 d forms a polygonal shape, such as octagonal shape, when seen from a top-view. The first metal portion 148 a overlaps the through via structure 108. The first metal portion 148 b and the second metal portion 148 d cover the first via portion 148 a and the second via portion 148 c. More specifically, the first via portion 148 a (shown in dash lines) and the second via portion 148 c (shown in dash lines) are directly below the first metal portion 148 a and the second metal portion 148 d.

FIG. 3 shows an enlarged representation of the region A in FIG. 1Q in accordance with some embodiments of the disclosure. The bottom surface of first via portion 148 a has a first diameter Da, and the bottom surface of the first metal portion 148 b has a second diameter Db. The bottom surface of the second via portion 148 c has a third diameter Dc, and the bottom surface of the second metal portion 148 d has a fourth diameter Dd. The first diameter Da is smaller than the third diameter Dc, and the second diameter Db is smaller than the fourth diameter Dd. The second diameter Db is smaller than the third diameter Dc. In some embodiments, the first diameter Da is in a range from about 15 μm to about 20 μm, and the second diameter Db is in a range from about 18 μm to about 23 μm. In some embodiments, the third diameter Dc is in a range from about 40 μm to about 50 μm, and the fourth diameter Dd is in a range from about 45 μm to about 55 μm.

There is a first distance S₁ between the edge of the first via portion 148 a and the edge of the second via portion 148 c. In some embodiments, the first distance S₁ is smaller than the diameter of the second via portion 148 c of the conductive structure 148. In some embodiments, the first distance S₁ is in a range from about 10 μm to about 15 μm. If the first distance S₁ is smaller than 10 μm, the stress generated in the first via portion 148 a and the stress generated in the second via portion 148 c may not be balanced, and causing unwanted cracks. If the first distance is greater than 15 μm, the size of the conductive structure 148 may be too large and take up too much of the routing area.

Afterwards, as shown in FIG. 1H, a second passivation layer 150 is formed over the first passivation layer 140 and on the conductive structure 148, in accordance with some embodiments of the disclosure. Afterwards, a portion of the second passivation layer 150 is removed to form a third opening 151. The third opening 151 is directly over the second metal portion 148 d.

Next, as shown in FIG. 1I, an under bump metallurgy (UBM) layer 155 is formed in the third opening 151, and a conductive connector 156 is formed over the UBM layer 155, in accordance with some embodiments of the disclosure. The UBM layer 155 is directly over the second via portion 148 c of the conductive structure 148. The conductive connector 156 is electrically connected to the conductive structure 148 by the UBM layer 155. The conductive connector 156 overlaps a portion of the through via structure 108.

The UBM layer 155 may be made of conductive material, such as copper (Cu), copper alloy, aluminum (Al), aluminum alloy, tungsten (W), tungsten alloy, titanium (Ti), titanium alloy, tantalum (Ta) or tantalum alloy. In addition, the UBM layer 155 may contain an adhesion layer and/or a wetting layer. In some embodiments, the UBM layer 155 further includes a copper seed layer. In some embodiments, the UBM layer 155 includes an adhesion layer made of Ti/Cu and a wetting layer made of Cu. In some embodiments, the UBM layer 155 is formed by a plating process, such as an electrochemical plating process or an electroless process.

In some embodiments, the conductive connector 156 is made of a metal layer, such as copper, copper alloy, nickel, nickel alloy, aluminum, aluminum alloy, tin, tin alloy, lead, lead alloy, silver, silver alloy or a combination thereof. In some embodiments, the conductive connector 156 is formed by a plating process, such as an electrochemical plating process or an electroless process.

The conductive connector 156 includes a protruding portion 156 a and a top portion 156 b. The protruding portion 156 a is formed in the third opening 151, and the top portion 156 a is formed over the protruding portion 156 b. The protruding portion 156 a is extended toward to the interconnect structure 110 and the through via structure 108. The protruding portion 156 a is embedded in the first passivation layer 140. The dot line shown in FIG. 1I is drawn to provide a better understanding of the structure, but there is no actual interface or boundary between the protruding portion 156 a and the top portion 156 b.

Since the conductive structure 148 and the first passivation layer 140 are made of different material, the coefficient of thermal expansion (CTE) of the conductive structure 148 is mismatch that of the first passivation layer 140. As the size of the package structure 100 a minimizes, the CTE difference between the materials of a structure, e.g., passivation layers and conductive structure (RDLs), causes the stress accumulated in the conductive structure/passivation layer interface. In addition, since the conductive connector 156 is offset with respect to the through via structure 108, the stress on a first region, which is directly over the through via structure 108 and the stress on a second region, which is directly below conductive connector 156 are different and are not balanced. This unbalanced stress may cause the conductive structure to crack or voids to develop in the passivation layer during the packaging process.

It should be noted that since the through via structure 108 is not aligned with the conductive connector 156, the second via portion 148 c is directly below the conductive connector 156 to use as a support and to balance the stress. More specifically, the second via portion 148 c is directly below the protruding portion 156 a of the conductive connector 156 to reduce the stresses. Therefore, cracking is prevented and the reliability of the package structure 100 a is improved.

FIG. 1I′ shows a cross-sectional representation of a package structure 100 b, in accordance with some embodiments of the disclosure. The package structure 100 b is similar to, or the same as, the first package structure 100 a shown in FIG. 1I, except that an insulation layer 109 is formed between the substrate 102 and the first passivation layer 140. Processes and materials used to form the package structure 100 b may be similar to, or the same as, those used to form the package structure 100 a and are not repeated herein.

As shown in FIG. 1I′, the insulation layer 109 provides the insulation. It should be noted that no conductive material or layer is directly below or in direct contact with the second via portion 148 c of the conductive structure 148. The bottom surface of the second via portion 148 c is in direct contact with the insulation layer 109. In some embodiments, the insulation layer is made of silicon nitride or silicon oxide.

FIG. 4A-4B show cross-sectional representations of various stages of forming the first portion 148 ₁ and the second portion 148 ₂ of the conductive structure 148 of a package structure 100 c, in accordance with some embodiments of the disclosure. The package structure 100 c is similar to, or the same as, the first package structure 100 a shown in FIG. 1I, except that the top-view shape of the second via portion 148 c has a ring-shape.

As shown in FIG. 4A, the first opening 141 and the second opening 145 are formed in the first passivation layer 140. The second opening 145 has a first portion 145 a and a second portion 145 b, and the first portion 145 a is connected to the second portion 145 b to form a ring shape when seen from a top-view.

Afterwards, as shown in FIG. 4B, the conductive material is formed in the first opening 141 and the second opening 145 to form the conductive structure 148, in accordance with some embodiments of the disclosure.

The conductive structure 148 includes a first portion 148 ₁ and a second portion 148 ₂. The first portion 148 ₁ includes a first via portion 148 a in the first opening 141, and a first metal portion 148 b on the first via portion 148 a. The second portion 148 ₂ includes a second via portion 148 c in the second opening 145, and a second metal portion 148 d on the second via portion 148 c. The dot line shown in FIG. 1G is drawn to provide a better understanding of the structure, but there is no actual interface or boundary between the first via portion 148 a and the first metal portion 148 b, and between the second via portion 148 c and the second metal portion 148 d.

FIG. 4C shows a top-view representation of the first via portion 148 a and the second via portion 148 c taken along line C-C′ of FIG. 4B, in accordance with some embodiments of the disclosure. As shown in FIG. 4C, the second via portion 148 c has a ring shape when seen from a top-view.

FIG. 5A shows a top-view representation of the conductive structure 148, in accordance with some embodiments of the disclosure. FIG. 1G shows a cross-sectional representation of the package structure 100 a taken along line E-E′ of FIG. 5A, in accordance with some embodiments of the disclosure.

As shown in FIG. 5A, the through via structure 108 (the dot line) has a circular shape, the first via portion 148 a (the dot line) has a circular shape, and the second via portion 148 c (the dot line) has a circular shape when seen from a top-view. There is a first distance S1 between the first via portion 148 a and the second via portion 148 c. The bottom surface of the first via portion 148 a is in direct contact with the through via structure 108, and the bottom surface of the second via portion 148 c is in direct contact with the substrate 102.

FIG. 5B shows a top-view representation of positional relationship between the conductive structure 148 and the conductive connector 156, in accordance with some embodiments of the disclosure. FIG. 1I shows a cross-sectional representation of the package structure 100 a taken along line F-F′ of FIG. 5B, in accordance with some embodiments of the disclosure.

As shown in FIG. 5B, the conductive connector 156 is formed over the conductive structure 148. The conductive structure 148 has an octagonal shape, and the conductive connector 156 has an oval shape. The second via portion 148 c is located at about a central position related to the conductive connector 156. The first via portion 148 a is located at an edge position related to the conductive connector 156. The size of the second via portion 148 c is greater than the size of the first via portion 148 a. The formation of the second via portion 148 c is used to prevent the stress accumulated on some region and therefore to reduce the stress.

In some embodiments, there are two first via portions 148 a below the conductive structure 148. One of the first via portions 148 a is completely covered by the conductive connector 156, and the other of the first via portions 148 a is partially covered by the conductive connector 156. In some embodiments, the conductive structure 148 covers two first via portions 148 a and one second via portion 148 c. The number of first via portions 148 a may be greater than two and may be adjusted according to the actual application.

There is a ratio of the area of the second via portion 148 c to the area of the conductive connector 156 is in a range from about 30% to about 70%. When the ratio is within above-mentioned range, the stress can be reduced to effectively prevent the formation of cracks and voids. In addition, since the larger conductive connector 156 will transfer more stress from the substrate 102, the ratio of the area of the second via portion 148 c to the area of the conductive connector 156 should be designed within above-mentioned range to reduce the stress without affecting the routing.

FIGS. 6A-6E show cross-sectional representations of various stages of forming the package structure 100 d, in accordance with some embodiments of the disclosure.

As shown in FIG. 6A, a passivation layer 604 is formed over a substrate 602. In some embodiments, the substrate 602 is used as a temporary substrate. The temporary substrate provides mechanical and structural support during subsequent processing steps, such as those described in more detail later. The substrate 602 is made of a semiconductor material, ceramic material, polymer material, metal material, another suitable material, or a combination thereof. In some embodiments, the substrate 602 is a glass substrate. In some other embodiments, the substrate 602 is a semiconductor substrate, such as a silicon wafer.

The passivation layer 604 is deposited or laminated on the substrate 602 by an adhesive layer (not shown). The passivation layer 604 provides structural support for bonding an integrated circuit die, which will be described in more detail later, and helps reduce die shifting issues. In some embodiments, the passivation layer 604 is a polymer layer or a polymer-containing layer. The passivation layer 604 is a poly-p-phenylenebenzobisthiazole (PBO) layer, a polyimide (PI) layer, a solder resist (SR) layer, an Ajinomoto buildup film (ABF), a die attach film (DAF), another suitable layer, or a combination thereof.

An interconnect structure 610 is formed over the first passivation layer 604. The interconnect structure 610 may be used as a redistribution (RDL) structure for routing. The interconnect structure 610 includes multiple conductive layers 614 formed in multiple passivation layers 612. A conductive structure 648 is formed in the passivation layers 612. The conductive structure 648 includes a first portion 648 ₁ and a second portion 648 ₂. The first portion 648 ₁ includes a first via portion 648 a and a first metal portion 648 b. The second portion 648 ₂ includes a second via portion 648 c and a second metal portion 648 d.

Afterwards, a through via structure 608 is physically and electrically connected to the first via portion 648 a of the conductive structure 648. In some embodiments, the through via structure 608 is referred to as through interposer vias (TIVs).

In some embodiments, the through via structure 608 is made of copper (Cu), aluminum (Al), nickel (Ni), platinum (Pt), another suitable conductive material, or a combination thereof. In some embodiments, the through via structure 608 are formed using an electroplating process, a physical vapor deposition (PVD) process, a CVD process, an electrochemical deposition (ECD) process, a molecular beam epitaxy (MBE) process, an atomic layer deposition (ALD) process, or another applicable process.

As shown in FIG. 6B, a semiconductor die 620 is disposed on the interconnect structure 610 by an adhesive film 619, in accordance with some embodiments. In some embodiments, the front side (the active surface) of the semiconductor die 620 faces away from the interconnect structure 610. The back side (the non-active surface) of the semiconductor die 620 faces the interconnect structure 610. Afterwards, a package layer 650 is deposited over the interconnect structure 610. As a result, the through via structure 608 and the semiconductor die 620 are encapsulated by the package layer 650.

The semiconductor die 620 includes a substrate 621, a passivation layer 622, and conductive pads 624. A variety of device elements may be formed in or over the substrate 621. The device elements include active devices and/or passive devices. In some other embodiments, the device elements include image sensor devices, logic devices, memory devices, other applicable types of devices, or a combination thereof.

The adhesive film 619 is used to bond or attach the semiconductor die 620 and the interconnect structure 610. The adhesive film 619 includes a die attach film (DAF), another suitable layer, or a combination thereof. In some embodiments, the package layer 650 includes a polymer material. In some embodiments, the package layer 650 includes a molding compound.

Afterwards, as shown in FIG. 6C, a passivation layer 660 is formed over the package layer 650, in accordance with some embodiments. A conductive layer 664 is formed and embedded in the passivation layer 660. The conductive layer 664 is electrically connected to the through via structure 608 and the semiconductor die 620. The passivation layer 660 is made of dielectric material(s) and provides stress relief for bonding stress incurred during subsequent bonding processes.

Next, as shown in FIG. 6D, the structure as shown in FIG. 6C is flipped and attached to a carrier substrate 667, in accordance with some embodiments. Afterwards, the substrate 102 is removed to expose the passivation layer 604.

Afterwards, as shown in FIG. 6E, a UBM layer 675 is formed in the passivation layer 604 and a conductive connector 676 is formed over the UBM layer 675, in accordance with some embodiments. In addition, a semiconductor die 680 is formed over the passivation layer 604 by a conductive connector 682. In some embodiments, the conductive connector 676 has a height greater than that of the conductive connector 682.

The conductive connector 766 includes a protruding portion 676 a and a top portion 676 b formed over the protruding portion 156 b. The protruding portion 676 a is extended toward to the through via structure 608 and is embedded in the passivation layer 604. The dot line shown in FIG. 6E is drawn to provide a better understanding of the structure, but there is no actual interface or boundary between the protruding portion 676 a and the top portion 676 b.

The conductive connector 676 is electrically connected to the second via portion 648 c by the conductive layer 614 and the second metal portion 648 d. The second via portion 648 c is electrically connected to the through via structure 608 by the second metal portion 648 d, the first metal portion 648 b and the first via portion 648 a. The second via portion 648 c has one end to connect the second metal portion 648 d, and the other end is in direct contact with the package layer 650. There is no conductive material or layer is directly below and in direct contact with the second via portion 648 c.

It should be noted that the formation of the second via portion 648 c is used to prevent the stress accumulated on some region and therefore to reduce the stress. The second via portion 648 c provides a reliable support. Therefore, cracks and voids are prevented from forming, and the reliability of the package structure 100 a is improved.

Embodiments for forming a package structure and method for formation the same are provided. The package structure includes a through via structure formed in a substrate. A semiconductor die is formed below the through via structure, and a conductive structure is formed over the substrate. The conductive structure includes a first portion and a second portion. The first portion includes a first via portion and a first metal portion. The second portion includes a second via portion and a second metal portion. A conductive connector is formed on the conductive structure. The first via portion is directly formed on the through via structure, and the bottom surface of the second via portion is direct contact with the substrate. The second via portion is used as a support to reduce the stress. The cracks and voids can be reduced. Therefore, the quality, the yield and reliability of the package structure are improved.

In some embodiments, a package structure is provided. The package structure includes a first through via structure formed in a substrate and a semiconductor die formed below the first through via structure. The package structure further includes a conductive structure formed in a passivation layer over the substrate. The conductive structure includes a first via portion and a second via portion, the first via portion is directly over the first through via structure, and no conductive material is directly below and in direct contact with the second via portion.

In some embodiments, a package structure is provided. The package structure includes a through via structure formed in a package layer and a first semiconductor die formed adjacent to the through via structure. The package structure includes a first via portion directly on the through via structure and a second via portion adjacent to the first via portion. The second via portion has a first end and a second end in a vertical direction, the first end is in direct contact with the package layer. The package structure also includes a first line portion formed on the first via portion, and a second line portion formed on the second via portion. The first line portion is connected to the second line portion, and the second end of the second via portion is in direct contact with the second line portion. The package structure further includes a connector formed on the second metal portion, and the connector includes a protruding portion, and the second via portion is directly below the protruding portion of the connector.

In some embodiments, a method for forming a package structure is provided. The method includes forming a through via structure in a substrate and forming a semiconductor die below the substrate. The method further includes forming a first passivation layer over the substrate and forming a first opening and a second opening in the first passivation layer. The first opening exposes the through via structure, and the second opening exposes the substrate, the first opening has a circular shape when seen from a top-view, and the second opening has a circular shape when seen from a top-view. The method also includes forming a conductive material in the first opening and the second opening, and over the first passivation layer to form a conductive structure. The conductive structure includes a first via portion in the first opening, and a second via portion in the second opening. The first via portion is directly over the through via structure, and the bottom surface of the second via portion is direct contact with the substrate.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

What is claimed is:
 1. A package structure, comprising: a first through via structure formed in a substrate; a semiconductor die formed below the first through via structure; and a conductive structure formed in a passivation layer over the substrate, wherein the conductive structure comprises a first via portion and a second via portion, the first via portion is directly over the first through via structure, and no conductive material is directly below and in direct contact with the second via portion.
 2. The package structure as claimed in claim 1, wherein the conductive structure further comprises a first line portion over the first via portion and a second line portion over the second via portion, the first line portion is in direct contact with the second line portion.
 3. The package structure as claimed in claim 1, wherein a bottom surface of the first via portion is level with a bottom surface of the second via portion.
 4. The package structure as claimed in claim 1, wherein the entirety of a bottom surface of the second via portion is in direct contact with the substrate.
 5. The package structure as claimed in claim 1, wherein the second via portion is separated from the first via portion by the passivation layer in the same horizontal level.
 6. The package structure as claimed in claim 1, further comprising: an under bump metallization (UBM) layer directly over the second via portion; and a connector formed over the UBM layer, wherein the connector comprises a protruding portion in the passivation layer, and the second via portion is directly below the protruding portion of the connector.
 7. The package structure as claimed in claim 6, wherein the connector overlaps the through via structure.
 8. The package structure as claimed in claim 1, further comprising: an interconnect structure formed below the first through via structure, wherein the interconnect structure is between the first through via structure and the semiconductor die.
 9. The package structure as claimed in claim 1, wherein the first via portion has a circular shape when seen from a top-view, the second via portion has a circular shape when seen from a top-view, the first via portion has a first diameter, the second via portion has a second diameter, and the second diameter is greater than the first diameter.
 10. The package structure as claimed in claim 1, further comprising: a second through via structure formed in the substrate, wherein the second via portion is between the first through via structure and the second through via structure.
 11. The package structure as claimed in claim 1, wherein the second via portion has a ring shape when seen from a top-view.
 12. A package structure, comprising: a through via structure formed in a package layer; a first semiconductor die formed adjacent to the through via structure; a first via portion directly on the through via structure; a second via portion adjacent to the first via portion, wherein the second via portion has a first end and a second end in a vertical direction, and the first end is in direct contact with the package layer; a first line portion formed on the first via portion; a second line portion formed on the second via portion, wherein the first line portion is connected to the second line portion, and the second end of the second via portion is in direct contact with the second line portion; and a connector formed on the second metal portion, wherein the connector comprises a protruding portion, and the second via portion is directly below the protruding portion of the connector.
 13. The package structure as claimed in claim 12, further comprising: an interconnect structure formed below the first semiconductor die, wherein the first via portion is electrically connected to the interconnect structure through the through via structure.
 14. The package structure as claimed in claim 12, wherein a distance between the first via portion and the second via portion is smaller than a diameter of the second via portion.
 15. The package structure as claimed in claim 12, further comprising: a second semiconductor die formed over the first semiconductor die, wherein the second semiconductor die is adjacent to the connector.
 16. The package structure as claimed in claim 12, wherein the second via portion has a circular shape when seen from a top-view, and a diameter of the second via portion tapers gradually from the second end to the first end.
 17. A method for forming a package structure, comprising: forming a through via structure in a substrate; forming a semiconductor die below the substrate; forming a first passivation layer over the substrate; forming a first opening and a second opening in the first passivation layer, wherein the first opening exposes the through via structure, the second opening exposes the substrate, the first opening has a circular shape when seen from a top-view, and the second opening has a circular shape when seen from a top-view; and forming a conductive material in the first opening and the second opening, and over the first passivation layer to form a conductive structure, wherein the conductive structure comprises: a first via portion in the first opening; and a second via portion in the second opening, wherein the first via portion is directly over the through via structure, and a bottom surface of the second via portion is direct contact with the substrate.
 18. The method for forming the package structure as claimed in claim 17, further comprising: forming a second passivation layer over the first passivation layer; forming a third opening in the second passivation layer to expose a portion of the conductive structure; and forming a connector in the third opening, wherein the second via portion is directly below the connector.
 19. The method for forming the package structure as claimed in claim 17, further comprising: forming a underfill layer covering the semiconductor die; and forming a package layer covering the underfill layer.
 20. The method for forming the package structure as claimed in claim 17, wherein the second via portion has a ring shape when seen from in a top-view. 